This invention relates to quantitative measurement of acids in polar organic solvents and also to the application of such measurements for performance control.
One application of the invention is to solid phase peptide synthesis.
To maximise the efficiency of solid phase peptide synthesis in an automated system the extent of progress of each stage of the process must be estimated by a reliable and sensitive monitoring procedure. Data obtained in this way may be used to form the basis of decision making structures in a synthesis instrument capable of monitoring its own performance and modifying its synthetic approach on the basis of its experience of past syntheses. The monitoring system is central to this enhanced performance.
On-line monitoring in solid phase peptide synthesis has been achieved in certain cases by the use of chromogenic reagents whose reaction may be detected by the use of a dedicated spectrophotometer (Dryland A. & Sheppard, R. C. 1986, J.Chem. Soc. Perkin Trans. I. 125-137, Cameron, L. Meldahl, M. & Sheppard R. C. 1987 J.Chem. Soc.Chem. Commun, pp 270-272). This approach leads to a significant cost increase both in capital outlay for the instrumentation and also in running costs in terms of the specialised reagents to allow this on-line monitoring. Commercial instruments using this technology are available (Pharmacia/LKB Biolynx 4170, Milligen Series 9000), but no direct use is made of the available data in this instrument. In addition this form of monitoring only permits the use of one of the two current chemical process technologies for the coupling (that based on the fluorenylmethoxycarbonyl, Fmoc, protecting group for the incoming amino acid). The use of Fmoc as a protecting group has not received universal acceptance. The alternative currently available protecting group tertiary butoxy carbonyl, t Boc may not be used.
The present invention has been made from a consideration of this problem.